The news comes as somewhat of a surprise after Halep enjoyed a superb 2014 season, reaching her first grand slam final at the French Open in June and finishing as runner-up to Serena Williams in last month's WTA Tour Finals.
Halep also climbed as high as second in the WTA rankings and currently occupies third spot.
Speaking about her decision to split with the Belgian coach, she wrote on Facebook: "My collaboration with Wim Fissette will come to an end, following a mutual agreement.
"It was a good and beautiful year. I want to thank him and wish him good luck in the future."
Halep enjoyed a major breakthrough on the WTA Tour in 2013, winning six titles and ending the year as world number 11, before linking up with Fissette in January.